Well...
The Leafs still owe Babs near $20Mill. They would have had to pay a lot more than $4Mill to make it worth his time.
Toronto, of course. Would only agree to release him to coach for Washington if he waived much of, or Wash took over his salary.
That said; Laviolette could be exactly the gunning play style required considering they still have John Carlson, Kuznetsov, Ovi, Vrana, Oshie, Backstrom...
And even that said; Laviolette became a reasonable defensive coach in Nashville. But I assume he is being hired to resume his high tempo style, considering the cache of high power forwards, lack of depth behind Carlson. He certainly does not have the D he had in Nashville, and he did not bother with defense so much before he arrived in Trotz's footsteps there,,,